Mentally retarded people are vulnerable to a wide range of emotional disorders, which are often unidentified or not responded to with appropriate services. In recent years, the problem has become worse as a result of deinstitutionalization of the mentally retarded. Today there are many more mentally retarded people with emotional disorders living in community-based facilities than was the case in the past. These people are requesting services at community mental health centers that are poorly prepared to serve mentally retarded people. Additionally, operators of large state institutions are finding that severe mental illness is a major reason why some mentally retarded people cannot leave the institution. This has led to the creation of costly units for the "dually diagnosed" in state mental health hospitals. One problem in meeting the growing demand for mental health services for mentally retarded people is a lack of knowledge. There has been so little research that scientists are still in the early stages of trying to develop valid measures, valid clinical assessment techniques, and appropriate therapies. The need to increase the supply of mental health services for mentally retarded people implies a need for a long term commitment to research on this topic. Funds are requested to convene the first scientific meeting on the mental health aspects of mental retardation. An exceptionally distinguished group of 55 invited scientists and scholars have committed to participate ;in the proposed conference. The specific aims of the conference are to provide researchers with an opportunity to meet one another and exchange ideas; to summarize past research on the mental health aspects of mental retardation; to suggest priorities for future research; to identify and try to resolve methodological issues; to suggest ethical standards for research; and to stimulate graduate and medical student interest in the topic.